Experimental Study On Polymer Flooding In Middle-low Permeability Reservoir Of No.2Block Of Pubei

No.2Block of Pubei in Daqing oilfield is a middle-low permeability reservoir. Theformation salinity is high. In the process of polymer flooding, it is not sure that if the commonpolyacrylamide polymer can suit the formation of No.2Block of Pubei. Hydrophobicassociating type of salt resistant polymer is a kind of multi-functional monomer compoundedpolymer with the characteristics of low relative molecular mass and high viscosity. Itsphysical and chemical properties can meet the requirements of polymer flooding in class iiand class iii reservoir. The research of this kind of resistant polymer can provide importantreference to optimize the way for polymer flooding and to enhance the recovery. Thus, thesubject that experimental study on improving oil recovery by polymer flooding in No.2Blockof Pubei is put forward in this paper.In this paper, indoor evaluation is conducted to evaluate the performance of the commonpolymer with middle relative molecular mass and salt resistant polymer with low relativemolecular mass. The analysis that whether the two polymers are adapt to the reservoir pore inNo.2Block of Pubei is conducted by mercury injection and hydrodynamic diametermeasurement experiment. The flow characteristics of the two kinds of polymers are measured.And the displacement mode is optimized by indoor physical simulation flooding experiments.The result shows that the salt resistant polymer has the better performance in salt resistance,shearing resistance and temperature resistance. The salt resistant polymer with the sameconcentration as the common polymer has the much higher viscosity than the common one.The salt resistant polymer with the high concentration has the lower viscosity stability. Saltresistant polymer is more suitable for the pore structure of No.2Block of Pubei. Comparedwith the common polymer, salt resistant polymer can plug the formation pore and improve thereservoir environment better. The resistance coefficient and residual resistance coefficient ofthe salt resistant polymer are both higher than the common one obviously. The resistancecoefficient and residual resistance coefficient of both the two polymers diluted by clear waterare higher than the polymers diluted by sewage. And salt resistant polymer shows the rulemore obviously. The salt resistant polymer diluted by sewage should be used in No.2Block ofPubei. The best injection concentration is700mg/L and the best injection volume is0.64PV.